The fine manual says  " After Effects can’t copy source files that are larger than 2 GB using the Collect Files command: you must copy them manually to the (Footage) folder in the Collect Files folder."
This doesn't seem to be true for 5.5 because it has Collected a 6GB file to my watch folder.  But would the 6Gb file cause a problem  for Watch folder or Render Engine operations?

I collected my project to a network folder. Set a #2 machine using RE to watch it. It picked up the job and started rendering. On the #1 machine that I created the project on, staying AE, I set the Watch folder and it started rendering. Good. Machines #1 and #2 working for me.
I then spent some time setting up a third machine. Installed Trial version of AE from my Master Collection installer. Installed QT, Avid codecs, Sapphire trial license, ISIS client.  Connected to the network drive, it sees all of the files. When I set up the watch folder in RE, it sees the files, runs through the files already created by the other machines, and then goes back to searching. no rendering.
I went back to #1 machine and stopped it rendering so I could check some things. #2 machine is still rendering in RE.  But now I can't get #1 machine to pick up the Watch render again. It's acting like machine #3 using either AE or RE.